4 Replies Latest reply on Sep 25, 2014 12:04 PM by onehorse

    1V8 for UART?

    onehorse

      Is the UART input limited to 1V8 so that a logic level converter needs to interface a Serial device hooked up to the Edison?

       

      How about a USB device hooked up to D+/D-?

        • 1. Re: 1V8 for UART?
          DiegoV_Intel

          Hi onehorse,

           

          I've just searched the datasheet of the FT232R USB UART IC used in the Mini Breakout Board, and apparently this IC has an integrated level converter for interfacing 1.8V and 5V logic, so I'll say that a logic level converter is needed. You can check the complete datasheet here: FT232R Datasheet

           

          For the USB port, the Edison Module Hardware Guide, page 15, says: "All Edison I/O (with the exception of USB) uses 1.8 V signaling.".

           

          Let us know if this information was helpful. Have a nice day!

           

          Regards,

          Diego.

          • 2. Re: 1V8 for UART?
            onehorse


            Hi Diego,

             

            Thanks for the reply.

             

            I took a look at the FTDI FT232R Data Sheet and yes, there is a logic level conveter to the RS232 application but that is to pull up the voltage from 5 V to the 9 V required by the RS232 interface.

             

            In the MCU UART example there is no logic level converter. While it makes sense to convert the UART signals to the 1.8 V needed by the Edison, it would be very helpful for my Edison add-on board design activities to see the schematic for the Mini breakout board and understand how the signals to/from the Edison are being handled. I'd hate to connect the wrong voltage inadvertently and destroy one of my few precious Edisons while the supply of these is so scarce!

             

            Kris

            • 3. Re: 1V8 for UART?
              DiegoV_Intel

              Hi onehorse,

               

              Here is the Mini Breakout Board Schematic: Breakout Board Schematic

               

              Check the documentation section because there are new documents available: Edison Documents. Have a nice day!

               

              Regards,

              Diego.

              • 4. Re: 1V8 for UART?
                onehorse

                Excellent! Thanks so much for your help!